Receiving apparatus and control method therefor

1. A digital broadcast receiving apparatus comprising: generating means for receiving a digital broadcast and generating a data stream from a digital broadcast signal having a desired modulation frequency; input means for inputting a data stream based on a digital broadcast from an external digital broadcast receiving apparatus; playback means for playing back a content of a channel contained in one of the data streams obtained by said generating means and input means; and storage means for storing a content of a channel contained in the data stream other than the data stream to be played back by said playback means in a data storage medium, wherein said input means comprises: acquisition means for acquiring a channel information indicative of a channel that can be received by the external digital broadcast receiving apparatus from the external digital broadcast receiving apparatus, and determination means for determining on the basis of the channel information acquired by said acquisition means whether the external digital broadcast receiving apparatus can receive a digital broadcast signal containing a desired channel, and inputs the data stream from the external digital broadcast receiving apparatus that is determined by said determination means as an apparatus capable of receiving the desired channel.

2. The apparatus according to claim 1 , wherein said acquisition means and determination means are executed with respect to a plurality of external digital broadcast receiving apparatuses, which are connected via said input means to be able to input data streams, in order to find an external digital broadcast receiving apparatus that can receive the desired channel.

3. The apparatus according to claim 1 , wherein said acquisition means receives and acquires an NIT (Network Information Table) defined in the IEC 13818-1 MPEG2 SYSTEM from the external digital broadcast receiving apparatus, and said determination means analyzes the NIT acquired by said acquisition means to determine whether the external digital broadcast receiving apparatus can receive a desired channel.

4. The apparatus according to claim 3 , wherein said determination means comprises: first determination means for determining whether the desired channel is contained in the NIT acquired by said acquisition means; and second determination means for, when said first determination means determines that the desired channel is contained, inquiring of the external digital broadcast receiving apparatus whether the apparatus can execute reception of a digital broadcast signal containing the desired channel, thereby determining whether the desired channel can be received.

5. A digital broadcast receiving apparatus having generating means for receiving a digital broadcast and generating a data stream from a digital broadcast signal having a desired modulation frequency, comprising: notification means for notifying information of a channel that can be received in accordance with a request from an external digital broadcast receiving apparatus; control means for controlling said generating means in accordance with a request from the external digital broadcast receiving apparatus so as to generate a data stream from a digital broadcast signal having a modulation frequency containing a designated channel; and output means for outputting the data stream containing the designated channel, generated by said generating meals, to the external digital broadcast receiving apparatus.

6. The apparatus according to claim 5 , wherein said notification means provides an NIT (Network Information Table) defined in the IEC 13818-1 MPEG2 SYSTEM to the external digital broadcast receiving apparatus in accordance with a request from the external digital broadcast receiving apparatus.

7. The apparatus according to claim 5 , wherein said input means includes a network connection or bus connection to the external digital broadcast receiving apparatus.

8. A digital broadcast receiving system in which a plurality of digital broadcast receiving apparatuses are connected to each other via communication means so as to be able to communicate with each other, comprising: generating means for receiving a digital broadcast and generating a data stream from a digital broadcast signal having a desired modulation frequency in a first digital broadcast receiving apparatus; input means for allowing the first digital broadcast receiving apparatus to input a data stream based on a digital broadcast from an external digital broadcast receiving apparatus via the communication means; playback means for allowing the first digital broadcast receiving apparatus to play back in real time a content of a channel contained in one of the data streams respectively obtained by said generating means and input means; and storage means for allowing the first digital broadcast receiving apparatus to store in a data storage medium a content of a channel contained in the data stream other than the data stream to be played back by said playback means, wherein said input means comprises: acquisition means for acquiring information of a channel that can be received from an external digital broadcast receiving apparatus via the communication means, and determination means for determining on the basis of the information of the channel acquired by said acquisition means whether the external digital broadcast receiving apparatus can receive a digital broadcast signal containing a desired channel, and inputs the data stream from the external digital broadcast receiving apparatus that is determined by said determination means as an apparatus capable of receiving the desired channel.

9. The system according to claim 8 , wherein said acquisition means and determination means are executed with respect to a plurality of external digital broadcast receiving apparatuses, which are connected via the communication means, in order to find an external digital broadcast receiving apparatus that can receive the desired channel.

10. The system according to claim 8 , wherein said acquisition means receives and acquires an NIT (Network Information Table) defined in the IEC 13818-1 MPEG2 SYSTEM from the external digital broadcast receiving apparatus, and said determination means analyzes the NIT acquired by said acquisition means to determine whether the external digital broadcast receiving apparatus can receive a desired channel.

11. The system according to claim 10 , wherein said determination means comprises: first determination means for determining whether the desired channel is contained in the NIT acquired by said acquisition means; and second determination means for, when said first determination means determines that the desired channel is contained, inquiring of the external digital broadcast receiving apparatus whether the apparatus can execute reception of a digital broadcast signal containing the desired channel, thereby determining whether the desired channel can be received.

12. A control method for a digital broadcast receiving apparatus having a generating step of receiving a digital broadcast and generating a data stream from a digital broadcast signal having a desired modulation frequency, comprising: a notification step of notifying information of a channel that can be received in accordance with a request from an external digital broadcast receiving apparatus; a control step of controlling the generating step in accordance with a request from the external digital broadcast receiving apparatus so as to generate a data stream from a digital broadcast signal having a modulation frequency containing a designated channel; and an output step of outputting the data stream containing the designated channel, generated in the generating step, to the external digital broadcast receiving apparatus.

13. A receiving apparatus comprising: reception means for receiving a digital broadcast signal and generating a first data stream in accordance with the digital broadcast signal; input means for inputting a second data stream from an external receiving apparatus; selection means for selectively outputting the first data stream generated by said receiving means and the second data stream input by said input means; and control means for detecting a channel that can be received by the external receiving apparatus and controlling selecting operation of said selection means in accordance with the detection result.

14. The apparatus according to claim 13 , wherein said apparatus comprises instruction means for designating a channel, and said control means controls selecting operation of said selection means in accordance with the channel designated by said instruction means and the detection result.

15. The apparatus according to claim 14 , wherein said reception means controls selecting operation of said selection means in accordance with a first determination result obtained by determining whether the designated channel is contained in a digital broadcast signal received by said reception means, and a second determination result obtained by determining whether the designated channel is contained in a channel that can be received by the external receiving apparatus.

16. The apparatus according to claim 14 , wherein said control means determines whether the designated channel is contained in a channel that can be received by the external receiving apparatus, and if the designated channel is contained, said control means controls said selection means so that said selection means alternately outputs the first data stream obtained from the digital broadcast signal received by said reception means and the second data stream input from said input means and containing the designated channel.

17. The apparatus according to claim 14 , wherein said control means determines whether the designated channel is contained in a channel that can be received by the external receiving apparatus, and if the designated channel is not contained, controls said selection means so as to output only the first data stream obtained from the digital broadcast signal received by said reception means.

18. The apparatus according to claim 13 , wherein said detection means receives an NIT (Network Information Table) defined in the IEC 13818-1 MPEG2 SYSTEM, and detects a channel that can be received by the external receiving apparatus on the basis of the received NIT.

19. The apparatus according to claim 13 , further comprising recording means for recording a data stream output from said selection means, and display means for displaying an image based on the data stream output from said selection means.

20. The apparatus according to claim 19 , wherein said apparatus comprises instruction means for designating a channel to be displayed on said display means, and said detection means detects a channel that can be received by the external receiving apparatus in accordance with an instruction from said instruction means during recording of the first data stream by said recording means.

21. The apparatus according to claim 19 , wherein said apparatus comprises instruction means for designating a channel to be recorded by said recording means, and said detection means detects a channel that can be received byte external receiving apparatus in accordance with an instruction from said instruction means during display of an image on a desired channel in the first data stream by said display means.

22. The apparatus according to claim 13 , further comprising instruction means for designating a recording channel to be recorded by said recording means and a display channel to be displayed by said display means, and extraction means fox extracting a data stream on the recording channel from a data stream output from said selection means to output the extracted data stream to said recording means and also extracting a data stream on the display channel to output the extracted data stream to said display means in accordance with an instruction from said instruction means.